1. Field of the Invention
The invention relates to a pressure infusion device, and in particular a pressure infusion device for squeezing out a syringe.
2. Description of Related Art
In the case of pressure infusion devices used for carrying out infusions of a liquid into a patient, a syringe containing a liquid is squeezed out continuously, the squeezed out liquid being supplied through a hose to the patient. A known pressure infusion device (U.S. Pat. No. 4,465,475) has an elongated tubular housing to which a first holder is secured for supporting the syringe cylinder. The housing contains a spindle drive and, out of its one end, there extends a slide displaceable along the housing axis and provided with a second holder adapted to be applied to the syringe ram. By rotating a spindle arranged in the housing, the slide is linearly displaced relative to the housing, whereby the syringe mounted in the pressure infusion device is squeezed out. The drive of the advance system is effected by an electric motor.
It has also been known to provide limit switches or early alarm switches at the pressure infusion device. The switches are responsive if a predetermined advance position is reached, so that an alarm is generated or the device is turned off if the syringe is empty or nearly empty. However, an additional expenditure is involved with such limit switches, and, furthermore, a regular check of their perfect functioning is necessary.
The known pressure infusion devices must comply with high precision requirements concerning the advance means and the electric drive, because their total working operation is preset to subsequently take place without being monitored. Therefore, once an infusion rate is set, it must be ensured that the infusion rate is maintained exactly for further operation. In addition, deviations due to manufacturing irregularities and variations in units must not be substantial.
It is an object of the present invention to provide a pressure infusion device in which the total infusion operation is monitored and controlled by ensuring that the infusion conditions are strictly observed.